This application is based upon claims the benefit of priority from the prior Japanese Patent Application No. 11-149998 filed May 28, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a segmentation technique for dividing, for example, a microscopic color image into connected regions uniform in features of the image such as color and luminance, and more particularly to the image segmentation apparatus, its method, and a recording medium in which a processing program is recorded.
Generally, typical techniques for dividing image regions include region growing method, edge extraction method, and feature space clustering method.
In the region growing method, when a small region of notice and an adjacent small region mutually have a same feature, the process for merging them into one region is repeated, and therefore the regions equal in the feature are grown gradually, and finally the region of the entire image is divided.
In the feature space clustering method, on the basis of density distribution of points mapped onto a feature space, points in the feature space are divided into clusters, and pulled back onto the image, and the region is divided.
In the edge extraction method, first, edges are detected from an image, and a closed region enclosed by the edges is regarded as one region.
Therefore, the region growing method takes an enormous time in processing.
The clustering method is difficult in processing if the cluster shape is obscure.
In the edge extraction method, edges are often discontinued, and it is hard to process edges not forming closed curves.
In an improved method to handle discontinued edges, edges near the edge end point are regarded as extension of discontinued edge, and they are connected together.
This is a technique of connecting the discontinued edges by force, but as shown in FIG. 4, it is a difficult problem to connect with which edge, and a wrong segmentation may occur if connected with a false edge.
A proposal to solved these problems is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 10-171992, but this is based on the region growing method, and it takes much time in processing.
The invention is devised in the light of the above background, and it is hence an object thereof to provide a method and apparatus for dividing an image into plural regions almost without over-segmentation and under-segmentation comprising means for decreasing connection errors of mutual ends of discontinued edges, and reducing means of over-segmentation regions occurring consequently, and more particularly a method and apparatus for dividing an image into plural regions of a shorter processing time than in region growing method, and a recording medium in which its processing program is recorded.
To achieve the object, an aspect of the invention provides an image segmentation apparatus for dividing an image into plural regions according to feature quantities of pixels for composing the image by a programmed computer comprising:
a divider for dividing the image into plural regions by using the separation degree of feature quantities of pixels for composing the image;
an alienation degree operator for determining the alienation degree of feature quantities between mutual regions, from the alienation degree of feature quantities of pixels enclosing the boundary of plural regions divided by the divider; and
a changer for changing the alienation degree of feature quantities of pixels enclosing the boundary of regions in a specific condition, by using the separation degree of feature quantities of mutual regions calculated by the separation degree operator.
To achieve the object, another aspect of the invention provides an image segmentation method for dividing an image into plural regions according to feature quantities of pixels for composing the image comprising the steps of:
dividing the image into plural regions by using the alienation degree of feature quantities of pixels for composing the image;
determining the alienation degree of feature quantities between interior and exterior region, from the separation degree of feature quantities of pixels enclosing the boundary of plural regions; and
changing the alienation degree of feature quantities of pixels enclosing the boundary of regions in a specific condition, by using the alienation degree of feature quantities of mutual regions.
Also to achieve the object, a still another aspect of the invention provides a recording medium storing a computer-readable processing program for dividing an image into plural regions, according to feature quantities of pixels for composing the image by a computer, the computer-readable processing program comprising:
a program encoder for causing the computer to divide the image into plural regions, by using the alienation degree of feature quantities of pixels for composing the image;
a program code portion for causing the computer to determine the alienation degree of feature quantities between mutual regions, from the alienation degree of feature quantities of pixels enclosing the boundary of plural regions; and
a program code portion for causing the computer to change the alienation degree of feature quantities of pixels enclosing the boundary of regions in a specific condition, by using the alienation degree of feature quantities of mutual regions.